C2 Core B;Gene-Targeting/Viral Vector Core C2.1 Rationale. Active genetic manipulation of mice and viral targeting of protein expression in neural tissue have resulted in a revolution in the study of the nervous system. Although interpretation of experiments involving genetic manipulation of mice must be performed with care, the ability to monitor changes in the CNS in vivo upon modification of a single gene makes this technique an indispensable tool for modern inquiry in neurobiology. The usefulness of genetically altered mice will grow even further with increased use of genetargeted mice expressing proteins deficient for specific protein-protein interactions, conditional knockouts, BAC-transgenics and animals expressing externally-triggered neuronal switches. Use of viral vectors to acutely alter protein expression is a powerful technique complementary to genetic manipulation. The group of NINDS researchers at the UCD AMC is using a variety of genetically altered mice and viral vectors to study fundamental questions in neurobiology. Although we have access to a the transgenic facility of the Charles C Gates Regenerative Medicine and Stem Cell Biology Program to produce gene targeted mice, the point of entry is a finished transgenic vector or transfected ES cells (see Appendix, letter from Dr. Peter Koch). Moreover, if Core B did not exist ES clone screening by PCR and/or Southern blotting - all labor intensive procedures - would have to be performed by the individual investigator. For transgenic mice, several lines are obtained for each construct injected. These lines then need to be tested initially to see if they have integrated the exogenous DNA. Subsequently, analysis of appropriate tissue-specific transgene expression is necessary, as well as the analysis of germ-line transmission. These ES and transgenic studies all require skills in molecular biology and mouse husbandry that are not the areas of expertise of the majority of investigators. Likewise, construction and production of viral vectors also requires specific expertise that is not easily established in most laboratories individually. Core B provides these specialized services to RMNDC users.